1,526 research outputs found
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PHASE 1 Technical Letter Report – TS-00358: Portable Acoustic Contraband Detector
This TLR provides the results of all PNNL managed activities on this project, and contains a description of the data acquisition configuration and testing protocols, results and conclusions from this work. This TLR is part of the final deliverables package submitted to the client during the Phase 1 Go/No-Go meeting in Richland, Washington, on July 31, 2007
Density and Flow-Velocity Measurement Technology for Dredging Applications - Proof of Concept Study
This technical letter report provides the results of all PNNL managed activities on this project, and contains a description of the data acquisition configuration and testing protocols, results and conclusions from this work. This technical letter report constitutes the final deliverable to be submitted to the client for this proof-of-concept study
Evaluation of Manual Ultrasonic Examinations Applied to Detect Flaws in Primary System Dissimilar Metal Welds at North Anna Power Station
During a recent inservice inspection (ISI) of a dissimilar metal weld (DMW) in an inlet (hot leg) steam generator nozzle at North Anna Power Station Unit 1, several axially oriented flaws went undetected by the licensee's manual ultrasonic testing (UT) technique. The flaws were subsequently detected as a result of outside diameter (OD) surface machining in preparation for a full structural weld overlay. The machining operation uncovered the existence of two through-wall flaws, based on the observance of primary water leaking from the DMW. Further ultrasonic tests were then performed, and a total of five axially oriented flaws, classified as primary water stress corrosion cracking (PWSCC), were detected in varied locations around the weld circumference
The assembly history of the nearest S0 galaxy NGC 3115 from its kinematics out to six half-light radii
Using new and archival data, we study the kinematic properties of the nearest
field S0 galaxy, NGC 3115, out to half-light radii ()
from its stars (integrated starlight), globular clusters (GCs) and planetary
nebulae (PNe). We find evidence of three kinematic regions with an inner
transition at from a dispersion-dominated bulge
() to a fast-rotating disk (), and then an additional transition from the disk to a slowly rotating
spheroid at , as traced by the red GCs and PNe (and
possibly by the blue GCs beyond ). From comparison with
simulations, we propose an assembly history in which the original progenitor
spiral galaxy undergoes a gas-rich minor merger that results in the embedded
kinematically cold disk that we see today in NGC 3115. At a later stage, dwarf
galaxies, in mini mergers (mass-ratio 1:10), were accreted building-up the
outer slowly rotating spheroid, with the central disk kinematics largely
unaltered. Additionally, we report new spectroscopic observations of a sample
of ultra-compact dwarfs (UCDs) around NGC 3115 with the Keck/KCWI instrument.
We find that five UCDs are inconsistent with the general rotation field of the
GCs, suggesting an \textit{ex-situ} origin for these objects, i.e. perhaps the
remnants of tidally stripped dwarfs. A further seven UCDs follow the GC
rotation pattern, suggesting an \textit{in-situ} origin and, possibly a GC-like
nature.Comment: 22 pages (including 3 pages of Appendix material), 14 figures,
published in MNRA
Verification and Validation of Computational Models for Ultrasonic Testing
The Pacific Northwest National Laboratory (PNNL) is conducting confirmatory research for the U.S. Nuclear Regulatory Commission (NRC) for the verification and validation of computational models used in ultrasonic testing (UT). This paper discusses some of the findings obtained from simple geometrical reflectors in isotropic, fine-grained, homogeneous materials with conventional ultrasonic transducers. A total of 348 ultrasonic raster scans were acquired using pulse-echo conventional probes with different diameters, beam angles, wave modalities, and frequencies. The raster scans contained reflections from machined notches (flaws) of different sizes and orientations. High frequency pencil beam models, and flaw scattering models employing the Kirchhoff and geometric theory of diffraction approximations, were then used to simulate the corresponding experimental measurements. CIVA, a semi-analytical nondestructive evaluation (NDE) simulation platform developed by the French Commissariat à l’Energie Atomique (CEA), was used to run simulations based on the approximation models. The experimental measurements were compared to their modeled counterparts using quantitative metrics obtained from the C-scans, B-scans and A-scans. To address uncertainties in the input parameters to the computational model, parametric studies and sensitivity analyses were conducted on all the relevant inputs. Sources of discrepancies between the experiment and simulated results are discussed in terms of numerical model errors and uncertainties in the experiments and model input parameters
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Syndemics and the PrEP Cascade: Results from a Sample of Young Latino Men Who Have Sex with Men.
Young Latino men who have sex with men (MSM) are a highly vulnerable population for HIV infection. Pre-exposure prophylaxis (PrEP) is a novel biomedical HIV prevention tool that may aid in reducing the disparity in HIV incidence among Latino MSM. However, PrEP use is disproportionally low among Latino MSM and, therefore, identifying barriers along the PrEP continuum of care (the "PrEP cascade") would provide insight into how to best deploy PrEP interventions. Syndemics theory is a prominent framework employed in HIV prevention; however, to date, no known studies have applied this theory to PrEP. Thus, the aim of the current study was to explore the association between syndemics and the PrEP cascade, including the degree to which psychosocial and structural syndemic constructs are related to the PrEP cascade. Participants were 151 young Latino MSM (M age = 24 years; SD = 3) residing in San Diego, California, who completed a battery of online self-report measures. Results indicated high levels of syndemic indicators and varying levels of engagement across the PrEP cascade. As syndemic indicators increased, the odds of engagement across the PrEP cascade were significantly lowered. Psychosocial and structural syndemic factors accounted for unique variance in the PrEP cascade. Results highlight the need for combination interventions that address both psychosocial and structural barriers to PrEP use and persistence among young Latino MSM
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Density and Flow-Velocity Measurement Technology for Dredging Applications - Proof of Concept Study
This technical letter report provides the results of all PNNL managed activities on this project, and contains a description of the data acquisition configuration and testing protocols, results and conclusions from this work. This technical letter report constitutes the final deliverable to be submitted to the client for this proof-of-concept study
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Field Evaluations of Low-Frequency SAFT-UT on Cast Stainless Steel and Dissimilar Metal Weld Components
This report documents work performed at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, and at the Electric Power Research Institute's (EPRI) Nondestructive Examination (NDE) Center in Charlotte, North Carolina, on evalutating a low frequency ultrasonic inspection technique used for examination of cast stainless steel (CSS) and dissimilar metal (DMW) reactor piping components. The technique uses a zone-focused, multi-incident angle, low frequency (250-450 kHz) inspection protocol coupled with the synthetic aperture focusing technique (SAFT). The primary focus of this work is to provide information to the United States Nuclear Regulatory Commission on the utility, effectiveness and reliability of ultrasonic testing (UT) inspection techniques as related to the inservice ultrasonic inspection of coarse grained primary piping components in pressurized water reactors (PWRs)
Field Evaluations of Low-Frequency SAFT-UT on Cast Stainless Steel and Dissimilar Metal Weld Components
This report documents work performed at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, and at the Electric Power Research Institute's (EPRI) Nondestructive Examination (NDE) Center in Charlotte, North Carolina, on evalutating a low frequency ultrasonic inspection technique used for examination of cast stainless steel (CSS) and dissimilar metal (DMW) reactor piping components. The technique uses a zone-focused, multi-incident angle, low frequency (250-450 kHz) inspection protocol coupled with the synthetic aperture focusing technique (SAFT). The primary focus of this work is to provide information to the United States Nuclear Regulatory Commission on the utility, effectiveness and reliability of ultrasonic testing (UT) inspection techniques as related to the inservice ultrasonic inspection of coarse grained primary piping components in pressurized water reactors (PWRs)
Dynamical coupled-channel model of meson production reactions in the nucleon resonance region
A dynamical coupled-channel model is presented for investigating the nucleon
resonances in the meson production reactions induced by pions and photons. The
model is based on an energy-independent Hamiltonian which is derived from a set
of Lagrangians by using a unitary transformation method. By applying the
projection operator techniques,we derive a set of coupled-channel equations
which satisfy the unitarity conditions within the channel space spanned by the
considered two-particle meson-baryon states and the three-particle
state. We present and explain in detail a numerical method based on a
spline-function expansion for solving the resulting coupled-channel equations
which contain logarithmically divergent one-particle-exchange driving terms
resulted from the unitarity cut. We show that this driving term can
generate rapidly varying structure in the reaction amplitudes associated with
the unstable particle channels. It also has large effects in determining the
two-pion production cross sections. Our results indicate that cautions must be
taken to interpret the parameters extracted from using models which do
not include cut effects.Comment: 73 pages, 20 figure
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